test: add integration tests for Test-PSBuildPester (fixes #102)

tests/Test-PSBuildPester.tests.ps1

@@ -0,0 +1,81 @@
+Describe 'Test-PSBuildPester' {
+    BeforeAll {
+        $moduleManifestPath = Join-Path -Path $PSScriptRoot -ChildPath '../PowerShellBuild/PowerShellBuild.psd1'
+        Import-Module -Name $moduleManifestPath -Force
+    }
+
+    Context 'when tests pass' {
+        It 'invokes Pester and returns a result object' {
+            $testRoot = Join-Path -Path ([IO.Path]::GetTempPath()) -ChildPath ("psbuild-pester-pass-{0}" -f [guid]::NewGuid())
+            New-Item -Path $testRoot -ItemType Directory -Force | Out-Null
+
+            @'
+Describe "fixture pass" {
+    It "passes" {
+        1 | Should -Be 1
+    }
+}
+'@ | Set-Content -Path (Join-Path -Path $testRoot -ChildPath 'fixture.pass.tests.ps1') -Encoding utf8
+
+            $result = Test-PSBuildPester -Path $testRoot -OutputVerbosity None
+
+            $result | Should -Not -BeNullOrEmpty
+            $result.PassedCount | Should -Be 1
+
+            Remove-Item -Path $testRoot -Recurse -Force
+        }
+    }
+
+    Context 'when tests fail' {
+        It 'throws to signal failure' {
+            $testRoot = Join-Path -Path ([IO.Path]::GetTempPath()) -ChildPath ("psbuild-pester-fail-{0}" -f [guid]::NewGuid())
+            New-Item -Path $testRoot -ItemType Directory -Force | Out-Null
+
+            @'
+Describe "fixture fail" {
+    It "fails" {
+        1 | Should -Be 2
+    }
+}
+'@ | Set-Content -Path (Join-Path -Path $testRoot -ChildPath 'fixture.fail.tests.ps1') -Encoding utf8
+
+            { Test-PSBuildPester -Path $testRoot -OutputVerbosity None } | Should -Throw
+
+            Remove-Item -Path $testRoot -Recurse -Force
+        }
+    }
+
+    Context 'when code coverage is enabled' {
+        It 'writes coverage results to the requested output path and format' {
+            $testRoot = Join-Path -Path ([IO.Path]::GetTempPath()) -ChildPath ("psbuild-pester-coverage-{0}" -f [guid]::NewGuid())
+            New-Item -Path $testRoot -ItemType Directory -Force | Out-Null
+
+            $targetFilePath = Join-Path -Path $testRoot -ChildPath 'target.ps1'
+            @'
+function Invoke-Target {
+    'ok'
+}
+'@ | Set-Content -Path $targetFilePath -Encoding utf8
+
+            @'
+. "$PSScriptRoot/target.ps1"
+
+Describe "fixture coverage" {
+    It "invokes target" {
+        Invoke-Target | Should -Be "ok"
+    }
+}
+'@ | Set-Content -Path (Join-Path -Path $testRoot -ChildPath 'fixture.coverage.tests.ps1') -Encoding utf8
+
+            $coverageOutputFile = 'coverage.xml'
+            $null = Test-PSBuildPester -Path $testRoot -OutputVerbosity None -CodeCoverage -CodeCoverageThreshold 0 -CodeCoverageFiles @($targetFilePath) -CodeCoverageOutputFile $coverageOutputFile -CodeCoverageOutputFileFormat JaCoCo
+
+            $coverageFilePath = Join-Path -Path $testRoot -ChildPath $coverageOutputFile
+            $coverageFilePath | Should -Exist
+            $coverageText = Get-Content -Path $coverageFilePath -Raw
+            $coverageText | Should -Match '<report\b'
+
+            Remove-Item -Path $testRoot -Recurse -Force
+        }
+    }
+}